I believe I answered you on Twitter, but if not then here you go.
Restart the computer.
Press <Ctrl>+<S> within four seconds after the <Ctrl>+<S> prompt appears. The message prompting to press <Ctrl>+<S> is displayed once for each Broadcom NetXtreme Gigabit Ethernet adapter you have in your computer. The messages are displayed in the same order as the assigned adapter-device number.
Use the up arrow and down arrow keys to move to up and down through the MBA Configuration menu.
Use the right arrow or left arrow key to change settings of the selected option. You will find WOL at the bottom.
Press <F4> to save your settings.
Press <Esc> when you are finished.
Let me know if this helps.